1. Field of the Invention
The present invention relates to an apparatus and method for reducing power consumption in a multi antenna system. More particularly, the present invention relates to an apparatus and method for reducing the power consumption of a Base Station (BS) in a multi antenna system.
2. Description of the Related Art
A multi antenna system transmits data using channels independent from each other by antenna. Thus, the multi antenna system can increase transmission reliability and throughput even without allocating an additional frequency or increasing transmission power as compared to a single antenna system.
The use of multi antennas provides an advantage that a transmission Power Spectral Density (PSD) of a BS becomes identical with the sum of transmission PSDs of respective transmit antennas. For example, assuming a 2×2 Multiple Input Multiple Output (MIMO) antenna configuration, the transmission PSD of the BS can be illustrated as in FIG. 1.
FIG. 1 illustrates a PSD of a BS in a multi antenna system according to the related art.
As illustrated in FIG. 1, the BS includes a Radio Frequency (RF) unit 100 for transmitting a signal using two transmit antennas. For example, the RF unit 100 includes a first path 120 for transmitting/receiving a signal through a first antenna, a second path 130 for transmitting/receiving a signal through a second antenna, and a transmitter/receiver 110 for processing RF signals transmitted/received through the first path 120 and second path 130. Here, the first path 120 and second path 130 each include a Front End Unit (FEU) and a power amplifier.
A transmission PSD of the BS can be represented as the sum of a first transmission PSD of the first antenna and a second transmission PSD of the second antenna. That is, assuming that the maximum radiated power of a signal that the BS transmits through each of the first antenna and the second antenna is equal to ‘A/2’, the maximum radiated power of the BS is equal to ‘A’.
In a case in which the amount of traffic is reduced, the number of Resource Blocks (RBs) used for transmission decreases and thus, the BS decreases an RF power transmitted through a power amplifier.
In a case in which the amount of traffic is reduced and thus the BS decreases the RF power as described above, the BS generates a signal of a lower output than the maximum output of the power amplifier. However, the power consumption of the BS is substantially the same irrespective of the magnitude of an output signal due to a source supply for a Direct Current (DC) bias of the power amplifier itself and the power consumption of the power amplifier. Accordingly, there occurs a problem that, in the case in which the amount of traffic is reduced, the BS cannot effectively reduce the power consumption.